Akt is a serine/threoine protein kinase that plays critical role in regulating apoptosis induced by a variety of different signals. It is likely to function as one of several signal integration points that determines whether a cell will survive. The identification of proteins that are substrates for Akt, and genes whose transcription is regulated in an Akt-dependent manner, is of fundamental biologic importance. Recently a novel transgenic mouse model has been developed by the Anderson lab in which a constitutively activated mutant of Akt has been expressed in the mammary gland, resulting in a suppression of apoptosis during involution following weaning. This system offers a unique opportunity to study Akt function and action in a complex biological system of interest to developmental biologists and cancer cell biologists. We propose to use twodimensional gel electrophoresis coupled with immunoblotting with anti-phospho-Akt substrate antibodies to identify putative substrates for Akt. The identity of candidate substrates will be determined using mass spectrophotometic approaches (MALDI-TOF and MS/MS sequencing). Furthermore, we propose to use DNA microarray analysis to identify genes whose transcription is regulated by Akt. These are ambitious goals, but critical experience and preliminary data can be developed during the proposed period of training.